The present invention relates to a bicycle chain hanger for maintaining tension in the drive chain when the rear wheel is removed from the bicycle. It is installed on the inside of the right seat stay about six inches up from the center of the axle slot in the rear wheel dropout. The chain is hooked over the hanger while the rear wheel is still in place. When the rear wheel is removed, the spring-loaded, lever-mounted idler wheel of the rear derailleur maintains tension on the chain, keeping it trained around the drive sprocket and the derailleur and preventing it from drooping when the bicycle is placed on a carrier rack, locked up to a post or otherwise stored or handled.
Bicycle chain hangers are known per se and are often provided on bicycles with steel frame tubes by brazing a stubby nail-like member to the seat stay. In bicycles with aluminum frames, brazing is very complex and difficult and is impracticable. Aluminum welding is not as difficult as brazing but is time consuming and results in undesirably large fillets. Furthermore, when a frame (either steel or aluminum) with a hanger already installed is painted, the hanger creates a "shadow" in the paint spray pattern, which makes it difficult to get a good paint finish in the region of the hanger.
In the aluminum frames of "Cannondale" bicycles produced by the assignee of the present invention, Cannondale Corporation, chain hangers have, previously to the present invention, been provided by installing a special nut, called a "Rivnut", in the tube wall and threading a custom-made cap screw with a shoulder at the juncture between a threaded tip and plain shank to keep it in the correct position in the nut. This arrangement is costly, and if the hanger should be bent or dislodged it is not easily replaced, a disadvantage which it shares with the brazed hangers on steel frames.